Skywatch Line for Wednesday, February 17th and Thursday, February 18th , 2016

This is the Dudley Observatory Skywatch Line for Wednesday, February 17th and Thursday, February 18th written by Louis Suarato

The 76% illuminated, waxing gibbous Moon rises at 12:53 p.m. Wednesday. As the sky darkens, and the constellations appear, you’ll notice that the Moon is at the top of Orion, and directly below open star clusters NGC 2175, NGC 2129, IC 2157, NGC 2158, and M35. Wednesday is the birth date of German astronomer Johann Tobius Mayer. Born in 1723, Mayer’s development of accurate lunar tables, enabled navigators to determine longitude more precisely than ever before. Latitude could be determined by finding the altitude of the Sun at noon, or the North Star’s altitude at night, but in the 1700’s and before, calculating longitude was a challenge. Mayer’s tables made it possible to use the Moon’s apparent motion relative to the stars to calculate Greenwich Mean Time. Once Greenwich Mean Time was known, longitude could be calculated by converting one hour of time difference to 15 degrees of longitude. Mayer’s method was accurate to within a half degree of longitude. The Moon sets at 3:45 a.m. Thursday.

There will be an extremely bright International Space Station pass over our region beginning at 6:58 p.m. Wednesday evening. Look to the west-northwest horizon to see the ISS rise past the Great Square of Pegusus, and higher close to the Andromeda Galaxy. At its zenith, the ISS will fly over the Pleiades star cluster and Aldebaran, before continuing on past Betelguese in Orion, before ending its long, bright trek over the southeast horizon.

February 17th is also the anniversary of the launch of the NEAR spacecraft from Cape Canaveral on a Delta-2 rocket. Renamed NEAR Shoemaker in March 2000, to honor Dr. Eugene Shoemaker, the legendary geologist whose research increased our knowledge of how comets and asteroids shaped the planets. The main objectives of the NEAR mission were to land on the first asteroid ever discovered, 433 Eros, and study the physical geology, composition and geophysics of the asteroid. NEAR also sought to clarify the relationship between asteroids, comets and meteorites. NEAR touched down on the asteroid Eros and began to transmit data from the surface on February 12, 2001, becoming the first spacecraft to land on an asteroid.

While the Moon is setting, Mars and Saturn will be rising over the eastern horizon, separated by 22 degrees. Venus and Mercury rise after 5:30 a.m. Thursday, 4.3 degrees apart, but very low on the horizon before disappearing into the glow of sunrise.

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